深海鲣鱼(Katsuwonus pelamis)低温热泵联合干燥技术优化及品质分析

为了提高深海鲣鱼(Katsuwonus pelamis)干制品的质量,采用低温热泵联合干燥技术,对深海鲣鱼干制品的色差值、复水比、细菌总数、T-VBN值以及能耗值等指标进行分析测定。实验结果表明,低温热泵联合干燥技术较传统单一干燥技术在干燥效果、干燥能耗以及投入设备成本等方面更具有优势。进一步对影响低温热泵干燥技术的因素主要包括填物料量、循环风速、干燥室温度和相对湿度等进行优化。研究结果表明:深海鲣鱼(500g左右)在干燥室相对湿度控制35%、干燥室温度为45°C、装填物料量为8kg、循环风速为2.5m/s时候干燥效果最佳,并且节能效果明显,能耗降低达到35.2%。该成果的成功开发对降低水产品干燥过程中的耗能问题具有促进作用。     

Selected aspects of studies of sediments from the Ebro River （Spain） and the Dobczyce drinking water reservoir （Poland） within the frames of the European and national research projects

Mineral and organic matter either soluble or suspended are transported by the rivers and when deposited in the bed of the river or in the water reservoir, sediments are formed, whose chemical composition may serve as a fingerprint of the history of the ecosystem. The results of the studies of sediments in water systems （river catchments, reservoirs） can be used not only for the evaluation of the current state of the ecosystem but also to prevent any dangerous environmental changes. Bottom sediments can in many ways accumulate both suspended and soluble components. The process is influenced by several factors like pH, red-ox potential, oxygen content, interactions, etc. The complexity of those phenomena causes that in order to study the accumulation processes of compounds in sediments the application of various analytical techniques is required. The authors participate in two big projects on sediment studies. The AquaTerra Project is the EU funded project on understanding river-sediment-soil-groundwater interactions for support of management of river basins and catchment areas. Our group＇s studies are focused on mercury determination and its speciation in sediments and fish from the Ebro River in Spain. The Dobczyce Project is the national project funded by the Ministry of Education and sciences of Poland which is also a EU member country. The latter covers many aspects of accumulation and fate processes of chemical compounds in sediments of the reservoir which supplies 60% of drinking water to about one million population in the city of Krakow in Poland.     

Effect of swelling inhibitors on the swelling and stress relaxation of clay bearing stones

Clay-containing stones such as Portland Brownstone (USA), Villarlod Molasse (Switzerland) and Tarifa Sandstone (Spain), are expected to weather as a result of wetting and drying cycles. During drying events, contraction of the drying surface leads to stresses approaching the tensile strength of the stone. However, we have found that the magnitude of these stresses is reduced by the ability of the stone to undergo stress relaxation. In this paper we describe novel methods to determine the magnitude of the stresses and the rate at which they develop and relax. We also discuss the influence of swelling inhibitors on the magnitude of swelling and the rate of the stress relaxation of these stones. The implications of our findings for the understanding of damage due to swelling of clays are discussed.Special Issue: Stone decay hazards     

深圳湾海域环境容量及污染总量控制研究——I.潮汐、潮流数值模拟

基于美国普林斯顿大学的POM(Princeton Ocean Model)模型,将干湿网格技术引入到模型中,利用模型的外模式(二维)对深圳湾海域的潮汐、潮流和余流进行了数值模拟研究。模拟结果与实测值吻合较好。计算结果表明:深圳湾海域属不正规半日潮,水平潮流具有明显的往复流性质,主要呈西南—东北走向;落潮流速略大于涨潮流速;受地形及陆地河流径流的影响,湾中到湾口及航道附近流速较大,湾顶和靠近香港的滩涂部分流速较小;深圳湾余流场较弱,余流流向指向湾外;整个深圳湾水交换较弱,海域自净能力较差。     

WEATHERING BY WETTING AND DRYING: SOME EXPERIMENTAL RESULTS

A series of experiments on sandstone and dolerite was undertaken in an attempt to better understand the wetting and drying weathering process. As rock samples are frequently subjected to wet–dry cycles within the simulation of other weathering mechanisms (e.g. freeze–thaw), three common methods of moisture application were used and the influences of these evaluated. It was found that the method of moisture application could affect the nature of the weathering products resulting from wetting and drying. It was also observed that there were changes in the internal properties of the rock (e.g. porosity/microporosity) and that these could influence the synergistic operation of other weathering processes. Although not all of the observations could be explained, it is apparent that wetting and drying has both a direct and an indirect effect on the weathering of rock that has not been taken into account in simulations. Greater cognizance needs to be given to the role of this process both in the field and in laboratory simulations.     

土建筑遗址干湿耐久性研究

选择新疆交河故城原状生土试样和重塑土试样进行了干湿循环试验,之后进行了风洞试验和强度试验,研究土建筑的干湿耐久性。试验结果表明,在试样原始含水率比较低的情况下,试样首先经历了一个质量增大的过程,3个干湿循环后,试样的质量变化进入一个相对稳定的范围。随着增湿与脱湿过程中伴随的水分质量的变化,试样质量的整体趋势是减小的。随干湿循环次数增大,原状试样的强度减小,风蚀量增大,即耐久性持续变差。相反,随干湿循环次数增大,重塑样的强度反而增大,风蚀量减小,即耐久性有所提高。重塑样由于重塑过程中其微观结构受到破坏,强度弱化。干湿循环在某种意义上对重塑土起到“陈化作用”,愈合损伤的微结构。初期重塑土强度随干湿循环次数的增加逐渐增强,而后强度逐渐衰减抗风蚀能力减弱。     

干湿交替作用后砂岩破裂过程实时观测与分析

采用岩石破裂全过程的细观力学试验系统进行了天然状态及干湿交替作用后的完整和含预制圆孔砂岩试件的单轴压缩破裂试验。利用显微镜观察了砂岩裂纹萌生、扩展以及试件的失稳破坏过程。经过干湿交替作用后岩样更容易在较低的应力状态下发生裂纹的扩展,并且裂纹扩展的初始阶段一般表现为拉破裂。完整试件的裂纹是随机性的三维扩展,而有预制圆孔试件一般是从预制圆孔周边开始扩展。天然状态下的预制圆孔试件在起裂时从圆孔的压应力集中区产生剪切裂纹;而干湿交替作用后,起裂时可能先从拉应力集中区产生拉裂纹,并且裂纹演化过程更为复杂一些,破裂形式多样化。与天然状态相比,经过干湿循环作用后的砂岩破坏脆性降低,强度等力学参数也随干湿交替次数增加而逐渐降低。     

Modeling the impacts of drying trend scenarios on land systems in northern China using an integrated SD and CA model

Climate-induced drought has exerted obvious impacts on land systems in northern China. Although recent reports by the Intergovernmental Panel on Climate Change (IPCC) have suggested a high possibility of climate-induced drought in northern China, the potential impacts of such drying trends on land systems are still unclear. Land use models are powerful tools for assessing the impacts of future climate change. In this study, we first developed a land use scenario dynamic model (iLUSD) by integrating system dynamics and cellular automata. Then, we designed three drying trend scenarios (reversed drying trend, gradual drying trend, and acceleration of drying trend) for the next 25 years based on the IPCC emission scenarios and considering regional climatic predictions in northern China. Finally, the impacts of drying trend scenarios on the land system were simulated and compared. An accuracy assessment with historic data covering 2000 to 2005 indicated that the developed model is competent and reliable for understanding complex changes in the land use system. The results showed that water resources varied from 441.64 to 330.71 billion m³ among different drying trend scenarios, suggesting that future drying trends will have a significant influence on water resource and socioeconomic development. Under the pressures of climate change, water scarcity, and socioeconomic development, the ecotone (i.e., transition zone between cropping area and nomadic area) in northern China will become increasingly vulnerable and hotspots for land-use change. Urban land and grassland would have the most prominent response to the drying trends. Urban land will expand around major metropolitan areas and the conflict between urban and cultivated land will become more severe. The results also show that previous ecological control measures adopted by the government in these areas will play an important role in rehabilitating the environment. In order to achieve a sustainable development in northern China, issues need to be addressed such as how to arrange land use structure and patterns rationally, and how to adapt to the pressures of climate change and socioeconomic development together.     

BOM的动边界改进及其应用

针对河口海岸数值模拟的动边界问题,使用了一个简便的干湿网格法,对BOM(Burgen Ocean Model)模型进行了动边界改进。并将该模型应用于瓯江口海域进行数值模拟计算,计算结果表明实测值与计算值吻合良好,模型能够较好的模拟岸边界随潮位涨落的变动。